Belt conveyor for sheet material

ABSTRACT

A perforated conveyor belt for cardboard sheets and the like travels over a row of suction chambers sequentially evacuated in synchronization with the belt travel by a suction pump connected with the chambers through a rotary distributor valve in which the orifice of an exhaust conduit in the valve rotor sweeps circumferentially offset ports on the valve shell, the ports being connected to the chambers respectively. The circumferential width of the orifice may be adjusted for varying the number of simultaneously evacuated chambers. The valve rotor and the belt are driven synchronously by a common motor.

United States Patent [191 Matsuo Aug. 6, 1974 BELT CONVEYOR FOR SHEETMATERIAL [76] Inventor: Masaharu Matsuo, No. 3-17,

Chome, Higashi Komagata, Sumida-ku, Tokyo, Japan [22] Filed: Mar. 21,1973 [21] Appl. N0.: 343,382 Foreign Application Priority Data Sept. 11,1972 Japan ..47-90340 [52] US. Cl. 198/184, 137/625.ll [51] Int. Cl.365g 15/00, E03b [58] Field of Search 198/184; 271/74;

[56] References Cited UNITED STATES PATENTS l/l958 Bonner l37/625ill8/1965 lnsolio 271/74 9/1971 Kalven 271/74 l/l973 Shapiro l37/625.ll

3,750,832 8/1973 Ovarnstrom 221/211 Primary ExaminerRichard E. AegerterAttorney, Agent, or FirmHans Berman 57 ABSTRACT A perforated conveyorbelt for cardboard sheets and the like travels over a row of suctionchambers sequentially evacuated in synchronization with the belt travelby a suction pump connected with the chambers through a rotarydistributor valve in which the orifice of an exhaust conduit in thevalve rotor sweeps circumferentially offset ports on the valve shell,the ports being connected to the chambers respectively. Thecircumferential width of the orifice may be adjusted for varying thenumber of simultaneously evacuated chambers. The valve rotor and thebelt are driven synchronously by a common motor.

1 Claim, 5 Drawing Figures minnows w 3.827.548

SHEET 1 [IF 2' FIG. 2

BELT CONVEYOR FOR SHEET MATERIAL This invention relates to a beltconveyor, and particularly to a conveyor for cardboard blanks and likepieces of sheet material which need to be held to the conveyor belt bysuction.

When cardboard blanks are processed in a plurality of stages in themanufacture of cartons or the like by equipment consisting of individualunits connected by transfer conveyors, it is often important to maintainprecise alignment of the blanks with their direction of movement on theconveyor. It is usually preferred to employ belts in which perforationsextend between the two major belt faces, and to move the belt over openchambers in which at least a partial vacuum is maintained by a suitablepump. It is not desirable to maintain such vacuum at all times. It isparticularly undesirable to connect a chamber to the vacuum pump whilethe perforations in the belt are not covered by a conveyed sheet, andthus connect the chamber with the ambient atmosphere. It is not evendesirable nor necessary in many instances to connect all chamberssubjacent the traveling sheet with the pump since the power required fordriving the belt and the wear-inducing contact pressure between belt andchambers increase with the number of evacuated chambers.

It has therefore been proposed to equip a conveyor of the type describedwith sensitive limit switches, relays, and solenoid valves. The limitswitches sense the presence or absence of sheet material on the conveyorbelt, and they are connected with solenoid valves in the vacuum lines tothe individual chambers through relays to connect the vacuum pump onlyto selected chambers. Relay and solenoid coils cause a time lag betweenthe actuation of the limit switch and the opening of the valve, whichlag is unavoidable and not acceptable at very high conveyor speeds.Moreover, limit switches relay for operativeness on freedom fromcontaminants not always capable of being achieved under the conditionscommon in box manufacturing plants, and the known electrically operatedvacuum controls for belt conveyors of the type described requirerelatively frequent preventive maintenance operations even if theirrelatively sluggish response is acceptable.

The object of the invention is the provision of a suction-type conveyorin which proper synchronization between the evacuation of the suctionchambers and the movement of the conveyor belt is achieved at allpractical conveyor speeds and with great reliability over extendedperiods of operation without requiring overhaul or other maintenance ofthe vacuum controls.

With this object and others in view, the invention provides a conveyorof the type described with a rotary valve interposed between the suctionpump and the vacuum chambers under the conveyor belt which sequentiallyconnect the pump to the chambers. A common drive motor is connected tothe belt and to the valve for moving the belt in a closed loop and forsequentially connecting the chambers to the pump in timed sequence.

More specifically, the rotary valve includes an outer shell having anaxis and formed with ports angularly distributed relative to the axis.conduits respectively connect the ports to the chambers, and a rotormounted in the housing shell for rotation about the axis of the latterby the drive motor defines an exhaust conduit having two orifices ofwhich one sequentially sweeps the ports during rotation while the otherorifice is connected to the pump.

The performance characteristics of the vacuum system may be adapted tovarious conveyed materials by adjusting the circumferential width of theexhaust conduit orifice, and by thereby varying the number ofsimultaneously evacuated chambers.

Other features, additional objects, and many of the attendant advantagesof this invention will readily be appreciated as the same becomes betterunderstood by reference to the following detailed description of apreferred embodiment when considered in connection with the appendeddrawing in which:

FIG. 1 shows a conveyor of the invention in side elevation, and partlyin section, and the associated pneumatic circuit in a conventionalmanner;

FIG. 2 illustrates a valve in the circuit of FIG. 1 in side elevationalsection;

FIGS. 3 and 4 are front elevational sections of the valve of FIG. 2taken on the lines III-III and IVIV respectively; and

FIG. 5 shows the valve of FIG. 2 in rear elevational section on the LineV-V.

Referring now to the drawing in detail, and initially to FIG. 1, thereis seen an endless conveyor belt 10 trained over four pulleys 12. One ofthe pulleys 12 is driven by an electric motor 14 and draws the belt 10horizontally over the open tops of a row of ten contiguously justaposedsuction chambers 16. As is conventional in itself and not capable ofpictorial representation on the scale of FIG. 1, the major faces of thebelt 10 are connected by a multiplicity of perforations, and theorifices of the perforations in the bottom face of the belt communicatewith the chambers 16 when traveling over the same.

The chambers 16 are sequentially connected with a vacuum pump 18 by twosections 20, 22 of a rotary distributor valve more fully illustrated inFIGS. 2 to 5, each section having five suction ports 24 respectivelyconnected with associated chambers 16 by pipes 26. As indicated by abroken line, the valve sections 20, 22 are coupled to the motor 14 andthe driven guide pulley 12 for synchronous operation.

The distributor valve, as shown in FIG. 2, has an outer cylindricalshell 28 fixedly mounted on the supporting frame 30 of the belt conveyorwhich also carries the pulleys 12 in a known manner, not shown. Axiallyspaced ball bearings 32 in the shell 28 support the valve rotor whichincludes a partly hollow shaft 34. The solid axial end portion of theshaft 34 is coupled to the motor 14 by a gear transmission 36 includingbevel gears 38 on the shaft 34 and on the ouput shaft of thetransmission whose input shaft is coupled to the motor 14 in ananalogous manner.

Two flanged sleeves 40, 42 carry the inner races of the ball bearings 32and are rotatably mounted on the shaft 34. The sleeve on the solid endportion of the shaft 34 projects from the shell 28 and carries a clutchdisc 44 axially slidable on the sleeve 40, but secured against rotationby a key 46. In the illustrated position, the disc 44 is held in drivingconnection with the flange 48 fixed on the shaft 34 by a fork 50engaging a circumferential groove in the disc 44 in a manner notspecifically shown but well known in clutch disengaging mechanisms ofautomotive friction clutches. The fork 50 is pivotally mounted on theframe 30 and operated by means of a double-acting hydraulic or pneumaticcylinder 52 which is also mounted on the frame 32 and manuallycontrolled in a conventional manner, not shown.

A worm wheel 54 normally rotates freely on the sleeve 40 when a worm 55journaled in the frame 30 is turned by means of a non-illustratedhandwheel. The clutch disc 44 may be engaged with the worm wheel 54 bymeans of the cylinder 52, friction facings being provided on the axiallyopposite, radial engagement faces of the wheel 54, the disc 44, and theflange 48.

The tubular part of the shaft 34 has an internal annular shoulder 56which separates an inner portion 58 of the bore in the shaft 34 from anouter, wider bore portion. A coaxial tube 60 fixedly sealed in theshoulder 56 and the wider, tubular, axial portion of the shaft 34radially bound an annular conduit 62. The tube 60 axially projectsbeyond the shaft 34 through a cap 64 on the shell 28 and into a chamber66. The tube 60 is slidably sealed in the cap 64 whose cavity 68 freelycommunicates with the conduit 62. Respective radial openings 70, 72 inthe tubular portion of the shaft 34 connect the bore portion 58 and theconduit 62 with respective axial portions of the space between the shaft34 and the shell 28 which are separated from each other by an annulardisc-shaped partition 74. Suction lines 76, 78 respectively lead fromthe cavity 68 and the chamber 66 to the pump 18.

As is shown in FIGS. 3 and 4, two vanes 80, 82 are attached to thehollow portion of the shaft 34 by screws 84 on opposite axial sides ofthe partition 74. Two corresponding vanes 86, 88 are mounted onrespective pairs of axial bolts 90 between the partition 74 and theflanges of the sleeves 40, 42 so that the flanges are axially connectedby the bolts 90 and the partition 74 into a fixedly connected portion ofthe rotor which is normally coupled to the shaft 34 by the clutch disc44 for joint rotation.

The rotor thus defines two exhaust conduits of which one extends fromthe suction line 78 through the chamber 66, the tube 60, the boreportion 58, the opening 70 to an orifice circumferentially bounded bythe vanes 80, 86 and axially bounded by the flange of the sleeve 40 andthe partition 74. The other exhaust conduit extends from the suctionline 76 through the cavity 68, the annular conduit 62, the opening 72,to its orifice between the vanes 82, 88, the flanged sleeve 42 and thepartition 74. The partition axially separates the two groups of fiveports 24 of the respective valve sections 22, 22' arranged in the upperhalf of the cylindrical shell 28, the lower half being imperforate. Theopenings 70, 72 respectively associated with the valve sections and theassociated orifices are offset 180 relative to the axis of rotation ofthe shaft 34 so that the orifices of the two exhaust conduits sweep theten ports 24 consecutively and at uniform intervals during eachrevolution of the shaft 34.

In the illustrated relative angular position of the vanes 80, 82, 86, 88on the shaft 34 and between the flanged sleeves 40, 42, the orifices arewide enough only to connect one port 24 and the associated chamber 16 atone time to the pump 18, and the shaft 34 is synchronized with thepulleys 12 in such a manner that the belt progresses at the same rate asthe vacuum in the row of chambers 16. If a relatively light and stiffpiece of cardboard 92 is presented to the conveyor as is indicated inFIG. 1 in phantom view, the front end of the piece, as viewed in thedirection of belt movement, is attached to the belt 10 by the vacuum ina subjacent chamber 16 and travels thereafter with the belt, its frontend being held in contact with the belt by the vacuum produced by thepump 18. The vacuum gradually decays by leakage in the chambers shut offfrom the pump by the rotary distribution valve, and the piece ofcardboard is ultimately discharged from the conveyor belt 10 and free tobe grasped by the feed mechanism of the next machine in the productionline, not itself shown.

When blanks of relatively heavy or resilient material are to be conveyedon the belt 10, it may be desirable to secure them to the belt 10 byvacuum over much of their length, and the number of consecutive chambers24 which are simultaneously held at the highest available vacuum can beadjusted by shifting the vanes 86, 88 circumferentially away from thevanes 80, 82. For this purpose, the motor 14 is stopped, the clutch disc44 is disengaged from the flange 48 and engaged with the worm wheel 54,whereupon the latter is turned by means of the non-illustrated handwheelon the worm 55 until the desired orifice sizes of the two exhaustconduits are set. The setting is fixed by returning the clutch disc 44to the illustrated position.

The valve arrangement illustrated and described has been found morereliable than the combination of limit switches and solenoid valvesemployed heretofore. Its initial performance is better at high conveyingspeeds than that of the best available electromagnetic systems, and itsdurability is very great since it is immune to contaminants and does notrely for operativeness on absolutely tight seals between the movingvalve parts. It need not be built to extremely close tolerances, and isnot subject to deterioration by wear over long periods.

The division of the rotary valve into two sections 20, 22 respectivelycontrolled by the vanes 80, 86 and the vanes 82, 88 permits dynamicbalancing of the valve rotor in a manner not readily achieved otherwise,and essential for high-speed operation.

It should be understood, of course, that the foregoing disclosurerelates only to a preferred embodiment, and that it is intended to coverall changes and modifications of the example of the invention hereinchosen for the purpose of the disclosure which do not constitutedepartures from the spirit and scope of the invention set forth in theappended claims.

What is claimed is:

l. A conveyor comprising, in combination:

a. a perforated, elongated, endless belt having two opposite major facesand being formed with a multiplicity of perforations connecting saidfaces;

b. guide means for longitudinally guiding said belt in a closed loop;

0. a row of stationary chambers contiguously adjacent one of said facesand open toward the perforations in said one face;

(1. a suction pump;

e. rotary valve means operatively interposed between said pump and saidchambers for sequentially connecting said pump to said chambers; and

f. common drive means connected to said belt and to said valve means formoving said belt in said loop and for sequentially connecting saidchambers to said pump in timed sequence, said valve means including 6 1.an outer shell having an axis and formed with a said one orifice,

plurality of ports angularly distributed relative to 3. means forangularly moving said outer portion said axis, a plurality of conduitsrespectively conrelative to said inner portion about said axis, andnecting said ports to said chambers, for thereby varying thecircumferential width of 2. a rotor mounted in said shell for rotationabout 5 said one orifice,

said axis by said drive means, said rotor defining 4. clutch meansnormally coupling said outer poran exhaust conduit having two orifices,one of tion to said inner portion for joint rotation, and said orificessequentially sweeping said ports during said rotation, the other orificebeing con- 5. clutch disengaging means for disengaging said nected tosaid pump, said rotor having a radially 1O clutch means during saidangular moving of said inner portion and a radially outer portioncarryouter portion. ing respecive vanes circumferentially bounding

1. A conveyor comprising, in combination: a. a perforated, elongated,endless belt having two opposite major faces and being formed with amultiplicity of perforations connecting said faces; b. guide means forlongitudinally guiding said belt in a closed loop; c. a row ofstationary chambers contiguously adjacent one of said faces and opentoward the perforations in said one face; d. a suction pump; e. rotaryvalve means operatively interposed between said pump and said chambersfor sequentially connecting said pump to said chambers; and f. commondrive means connected to said belt and to said valve means for movingsaid belt in said loop and for sequentially connecting said chambers tosaid pump in timed sequence, said valve means including
 1. an outershell having an axis and formed with a plurality of ports angularlydistributed relative to said axis, a plurality of conduits respectivelyconnecting said ports to said chambers,
 2. a rotor mounted in said shellfor rotation about said axis by said drive means, said rotor defining anexhaust conduit having two orifices, one of said orifices sequentiallysweeping said ports during said rotation, the other orifice beingconnected to said pump, said rotor having a radially inner portion and aradially outer portion carrying respecive vanes circumferentiallybounding said one orifice,
 3. means for angularly moving said outerportion relative to said inner portion about said axis, and for therebyvarying the circumferential width of said one orifice,
 4. clutch meansnormally coupling said outer portion to said inner portion for jointrotation, and
 5. clutch disengaging means for disengaging said clutchmeans during said angular moving of said outer portion.
 2. a rotormounted in said shell for rotation about said axis by said drive means,said rotor defining an exhaust conduit having two orifices, one of saidorifices sequentially sweeping said ports during said rotation, theother orifice being connected to said pump, said rotor having a radiallyinner portion and a radially outer portion carrying respecive vanescircumferentially bounding said one orifice,
 3. means for angularlymoving said outer portion relative to said inner portion about saidaxis, and for thereby varying the circumferential width of said oneorifice,
 4. clutch means normally coupling said outer portion to saidinner portion for joint rotation, and
 5. clutch disengaging means fordisengaging said clutch means during said angular moving of said outerportion.